Adding or removing libraries to LIBS means that I have to add or remove things at two places in this .pro file. Since the libraries are the same for both windows and unix, i was wondering if I can write this shorter. I am using Qt 4.8, so reading the docs at http://doc.qt.io/qt-4.8/qmake-variable-reference.html#libs I found that I can probably replace the windows and unix scope by this one scope if I use the -l option:

LIBS += -lSomeCoolLib \
-lSomeOtherLib

However, on the same documentation page, the Note recommends against this and advises to explicitly specify the library to be used by including the .lib file name suffix, which would again mean having two scopes.

If the libraries on windows and unix are the same, then is there a way to specify them only once? Or should I stick with the two scopes and use .lib for windows and -l for unix?

As soon as paths or library names differ, you will have to use scoped declarations. Otherwise it really does not matter. Win32 also links correctly using -lSomeCoolLib, therefor you could just use one LIBS directive.